Digital television translator with PSIP update

ABSTRACT

A digital television translator includes a digital television receiver for receiving a first digital television signal at a first frequency and generating a digital transport stream from the first digital television signal. The digital transport stream can include original Program and System Information (PSIP) data having RX channel data that is indicative of the first frequency, the first major channel number, and/or the first minor channel number. The digital television translator also includes a PSIP update module for updating the original PSIP data in the digital transport stream by replacing the RX channel data with TX channel data. The TX data is indicative of a second frequency, a second major channel number, and/or a second minor channel number. The digital television translator further includes a digital television modulator for converting the digital transport stream having the updated PSIP data into a second digital television signal at the second frequency, where the second frequency can be the same or different from the first frequency.

This application is a Continuation application of U.S. patentapplication Ser. No. 10/890,210 filed on Jul. 14, 2004, which is acontinuation of U.S. patent application Ser. No. 09/545,913, filed onApr. 20, 2000, now U.S. Pat. No. 6,785,903. The prior applications areincorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a digital television translator. Moreparticularly, the present invention relates to a digital televisiontranslator that updates the program and system information protocol(PSIP) table with transmit (TX) channel data.

2. Discussion of the Related Art

Digital television (DTV) broadcasting systems are relatively new in theUnited States and offer many alternatives to traditional information andprogram distribution. In addition to traditional television programming,DTV systems offer the ability to distribute additional content in theform of data. This data can be any type of data including, for example,Internet data broadcast to one or more end users. Therefore, DTVbroadcast systems offer great flexibility and diversity in the types ofinformation they distribute. Like most conventional broadcast systems,DTV broadcast systems have a finite capacity limited by the bandwidth ofits channels.

Additionally, as with other broadcast systems, such as analog televisionsystems, the received DTV signal quality can vary greatly depending uponwhere the receiver is located. This problem is due to a number ofadverse propagation effects such as multi-path, interference, and simpleattenuation. One solution to this problem is to use multiple low powerrepeaters (On-Channel boosters) and/or translators (Re-modulators) toimprove reception in areas of poor DTV signal reception. For example, arepeater, placed in an area of poor signal reception, receives atransmitted signal from a high power DTV transmitter and re-transmits anamplified duplicate signal at the same frequency. Translators, on theother hand, can receive a transmitted signal from a high power DTVtransmitter and re-transmit the signal at a frequency different than thereceived frequency. Repeaters and translators are also used to extendthe coverage of a broadcast system incrementally, and economically, tospecific geographical regions.

FIG. 1 shows an example of a conventional DTV translator 1. Theconventional DTV translator includes a down converter 2, a first localoscillator 3, an up converter 4, and a second local oscillator 5. Areceived DTV signal (RX RF input) is down converted to IF (intermediatefrequency) by down converter 2. The IF is determined by the differencebetween the frequency LO1 generated by the first local oscillator 3 andthe RF frequency of the received DTV signal (RX RF Input). The IF signalis then up converted to RF by up converter 4. The frequency of the upconverted RF DTV signal (TX RF Output) is determined by the sum of thefrequency LO2 generated by the second local oscillator 5 and the IF. Theup converted DTV signal (TX RF Output) is then amplified andtransmitted. With this arrangement, the transmitted signal contains thesame information as the received signal, but is amplified. Further, whenLO1=LO2, the transmit frequency is the same as the received frequency,and the apparatus operates as an on-channel booster. Alternatively, whenLO1.noteq.LO2, the transmit frequency is different than the receivedfrequency, and the apparatus operates as a translator.

In the DTV American Television Systems Committee (ASTC) standard, a DTVsignal contains a Program and System Information Protocol (PSIP) table,which is a collection of hierarchically arranged sub-tables fordescribing system information and program guide data. One of sub-tablesin the PSIP table is the Virtual Channel Table (VCT), which contains alist of attributes for virtual channels carried in the digital transportstream (baseband information). VCT fields “major channel number” and“minor channel number” are used for identification. The major channelnumber is used to group all channels that are to be identified asbelonging to a particular broadcast corporation (or a particularidentifying number such as channel “12”). The minor channel numberspecifies a particular channel within the group. The VCT also contains a“carrier frequency” field, which is used to identify the frequency atwhich the DTV signal is transmitted and received. As discussed herein,TX and RX channel data include at least one of the following majorchannel number, minor channel number, carrier frequency, and/or otherdata necessary for generating a proper DTV signal.

When a RF DTV signal is translated to a new frequency by theconventional DTV translator 1 of FIG. 1, the PSIP table no longerreflects the correct carrier frequency. In many DTV receivers, thisdiscrepancy between the actual frequency of the received DTV signal andthe carrier frequency data contained in the PSIP table prevents thereceiver from properly receiving the DTV signal.

Also, a particular broadcast corporation may be assigned differentmajor/minor channel numbers in geographical regions serviced by eachtranslator. For example, Broadcast Corporation #1 could be assignedmajor/minor channel 12/04 in region #1 (served by a main DTVtransmitter) and major/minor channel 37/04 in region #2 (served by atranslator translating the main DTV transmitted signal). Theconventional translator of FIG. 1 therefore generates a translated DTVsignal that contains an incorrect channel number for transmission intoregion #2.

Moreover, in region #2, major minor/channel 12/04 may have already beenassigned to Broadcast Corporation #2. In that case, a single DTVreceiver in region #2 will receive two unique channels (BroadcastCorporation #1 and Broadcast Corporation #2) each having the samemajor/minor channel number in each of their PSIP tables. While some DTVreceivers overcome these anomalies by allowing users to select whetherto ignore PSIP data or to display the VCT information, other DTVreceivers do not have this capability and are unable to properly tune tothe program(s) of one or both of the two Broadcast Corporations.

SUMMARY OF THE INVENTION

Accordingly, the present invention relates to a digital televisiontranslator, and more particularly to a digital television translatorthat updates the PSIP table with proper channel and carrier frequencyinformation. To achieve these and other advantages and in accordancewith the purpose of the present invention, as embodied and broadlydescribed, there is provided a digital television translator, comprisinga digital television receiver for receiving a first digital televisionsignal and generating a digital transport stream from the first digitaltelevision signal, the digital transport stream including original PSIPdata having RX channel data; a PSIP update module for updating theoriginal PSIP data in the digital transport stream by replacing the RXchannel data with TX channel data; and a digital television modulatorfor converting the digital transport stream having the updated PSIP datainto a second digital television signal.

In another aspect of the instant invention, there is provided aninformation distribution network using digital television transmission,the information distribution network comprising a plurality of digitaltelevision transmission nodes including a main digital television signalsource for generating a main digital television signal; and a pluralityof digital television translators receiving a digital television signalfrom one of the plurality of digital television nodes, at least one ofsaid plurality of digital television translators including a digitaltelevision receiver for receiving the digital television signal from oneof the plurality of digital television nodes and generating a digitaltransport stream from the received digital television signal, thedigital transport stream including original ancillary data and originalPSIP data having RX data, a data update module for updating the originalPSIP data in the digital transport stream by replacing the RX channeldata with TX channel data and for replacing the original ancillary datain the digital transport stream with new ancillary data, and a digitaltelevision modulator for converting the digital transport stream havingthe new ancillary data and the updated PSIP data into a transmitteddigital television signal, wherein at least two of the plurality ofdigital television transmission nodes transmit at the same frequency andthe total ancillary data of the information distribution networkincludes the new ancillary data from multiple digital televisiontranslators of the plurality of digital television translators.

Additional features and advantages of the present invention will be setforth in the description that follows, and in part will be apparent fromthe description, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention thattogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 shows an example of a conventional DTV translator;

FIG. 2 shows a first embodiment of a DTV translator of the presentinvention having PSIP table update capability;

FIG. 3 shows an example of a PSIP update module;

FIG. 4 shows a second embodiment of a DTV translator of the presentinvention having both PSIP table update capability and a re-multiplexor;

FIG. 5 shows an example of the re-multiplexor; and

FIG. 6 shows an example of an information distribution network of thepresent invention using multiple translators.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

To overcome the problems associated with the prior art, i.e., tuningproblems with some DTV receivers due to incorrect PSIP tableinformation, the PSIP table information is updated by the translator toproperly reflect the new transmit carrier frequency and channel number.

FIG. 2 shows a first embodiment of a DTV translator 10 of the presentinvention having PSIP table update capability. The DTV translator 10includes an 8-VSB receiver 11, a PSIP update module 12, an 8-VSBmodulator 13, an RF power amplifier 14, and a transmitting antenna 15.The receiver 11 receives an 8-VSB DTV signal (RFi) that may have beenoriginally transmitted by a base station or another translator, over theair or by a cable. The receiver 11 processes the DTV signal according toASTC DTV standards to produce a digital transport stream (TS) containingMPEG2 video data, audio data, ancillary data, and PSIP data. The PSIPdata in the digital transport stream includes a major channel number, aminor channel number, and a carrier frequency, which together make upthe RX channel data. As shown, the receiver 11 is controlled by an input(RX Channel Select) which informs the receiver 11 of which carrierfrequency channel to tune.

The processing of the received DTV signal by the 8-VSB receiver 11 is inaccordance with ATSC DTV standards and, accordingly, can include downconversion, digitization, carrier synchronization, symbol clocksynchronization, frame and segment synchronization, matched filtering,equalization, bit-demapping, Trellis decoding, convolutionalde-interleaving, Reed-Solomon forward error correction (FEC) decoding,and de-randomizing.

The digital transport stream (TS) is then input into PSIP update module12. The PSIP update module 12 extracts the PSIP table data and updatesthe RX channel data with TX channel data. Specifically, the majorchannel number, the minor channel number, and the carrier frequencycontained in the PSIP VCT are updated. Updated major and minor channelnumbers are those numbers assigned to the broadcaster associated withthe transport stream content for the geographical region covered by theDTV translator. Sometimes the original and updated channel numbers willbe the same, for example when the translator is being used to fill in apoor reception area of the geographical area covered by the maintransmitter. At other times, the original and updated channel numberswill be different, for example, when the translator is being used toextend coverage into a geographical area not covered by the maintransmitter. In this instance, the broadcaster may be licensed tobroadcast in the translator's geographical area, but at a differentchannel.

Also, the carrier frequency of the DTV signal transmitted from thetranslator must be reflected in the PSIP VCT. In most instances, thetranslator will transmit at a different frequency than it receives,requiring the PSIP VCT to be updated with the new transmitted carrierfrequency. In some instances, the carrier frequency of the DTV signalcan be transmitted at the same frequency that it is received, such aswhen the translator system is being used as an on-channel booster. Ineither instance, the updated PSIP table is then reinserted back into thedigital transport stream.

Once the PSIP data is updated, the transport stream containing theupdated PSIP data is then input into the 8-VSB modulator 13. 8-VSBmodulator 13 processes the digital transport stream according to ATSCDTV standards to produce a DTV signal (Rfo) at the carrier frequencycontained in the VCT of the updated PSIP table data. As shown, 8-VSBmodulator 13 is controlled by input (TX Channel Select) which informsthe 8-VSB modulator 13 at which frequency to transmit the DTV signal.Alternatively, the 8-VSB modulator can detect the carrier frequencyinformation from the VCT of the DTV signal and transmit the DTV signalusing the detected carrier frequency.

8-VSB modulator 13 processes the transport stream having the updatedPSIP data according to ASTC terrestrial broadcast standards.Accordingly, this processing can include randomization, Reed-Solomonencoding, convolutional interleaving, symbol mapping, trellis encoding,and vestigial sideband filtering. After the digitally filtered signal isconverted to an analog signal, the signal is up converted to a transmitRF signal (RFo) at the transmit frequency determined by TX channelselect. The 8-VSB modulator 13 typically operates at a frequency of 54MHZ-216 MHZ and 470 MHZ-806 MHZ and has a maximum output power ofapproximately 1 milliwatt. A power amplifier 14 and transmitting antenna15 are usually added to the output of the 8-VSB modulator 13.

FIG. 3 shows an example of PSIP update module 12. The PSIP update module12 includes an extractor 16 for extracting the original PSIP data, aPSIP update block 18 for replacing the major/minor channel number andcarrier frequency contained in the PSIP table, and an inserter 17 forinserting the updated PSIP table data back into the transport stream. Asshown, the PSIP table data is extracted by extractor 16 and input intothe PSIP update block 18. The PSIP update block 18 replaces themajor/minor channel number and transmit carrier frequency contained inthe VCT (a sub-table of the PSIP table) while retaining the other PSIPdata. The PSIP update block 18 then substitutes an updated major/minorchannel number and transmit carrier frequency into the VCT. Thereafter,the updated PSIP table data is re-inserted back into the digitaltransport stream via inserter 17.

FIG. 4 shows a second embodiment of a DTV translator 20 of the presentinvention. The second embodiment includes an 8-VSB receiver 21, a PSIPupdate module 22, a re-multiplexor 23, and an 8-VSB modulator 24.Usually an RF power amplifier 25 and an antenna 26 are coupled to the8-VSB modulator 24. The structure and operation of the second embodimentis the same as the structure and operation of the first embodiment,except that a re-multiplexor 23 is added for introducing new ancillarydata into the digital transport stream.

The digital transport stream containing original ancillary data and theupdated PSIP table data is input into the re-multiplexor 23.Re-multiplexor 23 substitutes new ancillary data in place of theoriginal ancillary data in the digital transport stream. The digitaltransport stream is then sent to 8-VSB modulator 24 and converted into aDTV signal consistent with the operation as described in the firstembodiment. In this way, each translator can distribute new ancillarydata to user(s) in the translator's transmit range.

FIG. 5 is a block diagram of the re-multiplexor 23, which comprises ademultiplexor 27 and a multiplexor 28. As shown, the original ancillarydata, video data, audio data, and updated PSIP table data is containedin the input digital transport stream, which is demultiplexed intoseparate bit streams by de-multiplexor 27. The original ancillary datais terminated (discarded). The multiplexor 28 then combines the videodata, the audio data, the updated PSIP data, and new ancillary data backinto the output digital transport stream, which is then input to the8-VSB modulator 24.

The PSIP update step and the ancillary data insertion step are notrequired to take place in any particular order. For example, since thePSIP data has been separated into its constituent streams bydemultiplexor 27 of re-multiplexor 23, the PSIP table update step couldtake place in the re-multiplexor 23 by updating the major/minor channelnumber and carrier frequency. The updated PSIP table data could bereinserted into the digital transport stream by multiplexor 28. Or, forexample, the placement of the PSIP update module 22 and the multiplexor23 could be reversed. Moreover, only a portion of the original ancillarydata could be replaced with new ancillary data thereby allowing otherportions of the ancillary data to be transmitted downstream by thetranslator.

The second embodiment allows DTV broadcasting stations to increase theirdata broadcasting capacity every time a DTV translator is added. Forexample, adding a DTV translator increases the number of users andincreases the capacity for data transmission through employment of thenew ancillary data, which permits the insertion of data, such asInternet data. Downstream Internet data can be inserted as new ancillarydata by each translator and distributed to specific geographic regionsand users without the need for additional bandwidth.

FIG. 6 shows an example of a third embodiment of the invention whereinan information distribution network 30 uses a plurality of translatorsto increase the data capacity of the network. As shown, a plurality oftranslators, collectively labeled 31 a-31 d, translate and distribute aDTV signal in both a star and daisy-chain configuration.

The first translator 31 a receives a DTV signal containing originalancillary data 0, such as Internet download data at a frequency fo.Translator 31 a inserts ancillary data 1 and discards original ancillarydata 0, and then retransmits the modified DTV signal having ancillarydata 1 at a frequency f1. User 32 a receives ancillary data 1 fromtranslator 31 a. A second DTV translator 31 b receives the translatedDTV signal from translator 31 a at a frequency of f1, substitutesancillary data 2 for ancillary data 1, and then retransmits at afrequency f2. User 32 b receives the DTV signal transmitted fromtranslator 31 b along with ancillary data 2. User 32 d also receivesancillary data 1 from translator 31 a. A third DTV translator 31 creceives the translated DTV signal from translator 31 b at a frequencyof f2, substitutes ancillary data 3 for the ancillary data 2, andretransmits at a frequency f1. User 32 c receives the DTV signaltransmitted from translator 32 c along with ancillary data 3. DTVtranslators 31 a, 31 b, and 31 c are thus configured in a daisy-chainfashion with translators 31 a and 31 c being endpoints.

Further, a fourth DTV translator 31 d receives the translated DTV signalfrom translator 31 a at a frequency of f1, substitutes ancillary data 4for ancillary data 1, and then retransmits at a frequency f4. User 32 dreceives the DTV signal transmitted from translator 31 d along withancillary data 4. DTV translators 31 a, 31 b, and 31 d are therebyconfigured in a star fashion with DTV translator 31 a configured as ahub. Moreover, a variety of translator topologies can be employed totransmit unique ancillary data to each of a very large number of users,or a group of users, without requiring an increase in the bandwidth ofany single translator's transport stream or physical RF channel.

Even more efficient use of bandwidth can be achieved by allowingmultiple translators to use the same transmit frequencies, as doestranslators 31 a and 31 c. Translators can be placed in any number ofconfigurations to increase the data capacity of the DTV distributionnetwork. Furthermore, the use of a PSIP update model in each of thetranslators can insure proper DTV reception.

Moreover, while the embodiments described herein can be implemented viacurrent ASTC standards, it is contemplated that other DTV standards or amodified ASTC standard could be readily employed to realize the presentinvention. Further, while the video data on the digital transport streamcan be MPEG2 standard video data, as described herein, the inventioncontemplates using variations of MPEG2 standard data in the digitaltransport system.

As the present invention may be embodied in several forms withoutdeparting from the spirit or essential characteristics thereof, itshould also be understood that the above-described embodiments are notlimited by any of the details of the foregoing description, unlessotherwise specified, but rather should be construed broadly within itsspirit and scope as defined in the appended claims, and therefore allchanges and modifications that fall within the meets and bounds of theclaims, or equivalence of such meets and bounds are therefore intendedto be embraced by the appended claims.

1. A system for translating a first digital transport stream containingone or more digital television programs carried in the first digitaltransport stream, comprising: a program information update unit, theprogram information update unit supplementing one or more attributes fora virtual channel of a digital television program carried in the firstdigital transport stream; and a multiplexor, the multiplexor combiningthe one or more attributes supplemented by the program informationupdate unit and the first digital television program carried on thefirst digital transport stream to form a second digital transportstream.